The ocean shots required three different simulation tools depending on the complexity of the shot. Frantic used Flood:Surf to create the overall ocean surface, with hooks to feed into particle systems for the ocean foam, mist and rain hits as well direct object-to-water interactions.

The ocean surface could be displayed as a low-resolution proxy, so that Frantic’s animators could animate against it. When rendered via the nVidia Gelato renderer, all the subpixel displacement needed for a believable liquid surface was included. When characters or objects interacted with the ocean surface, Flood:Core provided the key displacement of the water, which was combined with the ocean surface simulations.

For the interaction shots that resulted in particles and spray, Flood:Spray simulated key splashes and interactive events.

Getting physical

Much of the raft scene involved the live actors directly interacting with the CG sea creatures, including a shot where Trevor wrestles a particularly monstrous razorfish.

Actor-to-digital character interaction is always tricky, says Harvey, doing it in stereoscopic is even tougher. “Depth perception tells the viewer if an object is in front of or behind something, so we had to keep that in mind when creating and animating the sea characters,” says Harvey.

“Working in stereo meant an effect just looking right was not good enough, it had to be bang on right! And that meant right at a sub-pixel level. It almost sounds ridiculous, but a sub-pixel transform can be the difference between the fish appearing in an actor’s hand or it appearing six inches behind it in stereo space.”

As Journey to the Centre of the Earth is the first stereoscopic project for Frantic Films, the studio had to create a new stereo pipeline, as well as build new screening rooms in both its offices, allowing VFX artists to review the sequences in stereo.

The studio looked at three different approaches before devising a process to composite in stereo, with the left and right eye accounted for at the same time.

Custom plug-ins were built by Frantic Films’ VFX R&D team led by Mark Wiebe, including one for Eyeon Fusion that manages the left and right eyes and separates them, so that while compositing a shot the artists could preview any element of the shot in stereo.

Stereo work is traditionally done by working on the left-eye frame and then the right. Mike Shand, visual-effects supervisor, says: “We felt really good with our process of doing the compositing and effects simultaneously on each eye as one doublewide image, because right away, we had a review image in stereo. Every shot was in stereo at every level of completeness.“

Frantic Films VFX wrote custom tools to extract metadata data from the 3D cameras used to shoot the live-action, and used it to generate the second camera. The tools allowed for tweaking to correct imperfections in the information recovered from the footage.

“The fact that it was in stereo added plenty of issues to what was already a very challenging project,” says Harvey. “But the challenges made the whole experience that much more rewarding.”

Frantic Films resorted to creating its own proprietary software to handle the demands of the ocean scenes.

Interactions between characters and digital creatures were tricky, especially as the stereoscopic 3D format left very little room for error.

A beastly task

Along with the usual dinosaur reference materials, the Frantic team studied the flippers of killer whales, turtles and other large marine beasts when sketching the giant plesiosaurs that feature in the storm sequence.

“Although the concept art for the plesiosaur had been approved by the production team, a little later on the producers wanted a redesign, so we sat our lead creature modeller down and told him to go nuts,” says Chris `Harvey.

“So he used all the previous reference materials, and then some more of crocodiles, and he eventually came up with some great new concept art which became the dinosaur you see in the movie.”